When Cynthia Sigler called her sister to tell her she’d just given birth to a 13-pound, 14-ounce baby boy on Thursday at Tri-City Medical Center in Oceanside, her sister didn’t believe her.

“So, we took a picture of the scale and sent it to her,” Sigler said.

On Friday, Sigler cuddled her mop-headed, rosy-cheeked baby, who responded with massive yawns and a couple of gurgles. Jayden was born by Caesarean section.

He is almost twice the size of the average newborn, and medical staffers at most hospitals around the county couldn’t recall a bigger infant.

“He’s the largest baby I’ve ever delivered,” said Dr. Jerald White, Sigler’s obstetrician. White said he has delivered 20,000 babies since he began practicing medicine in 1964.

Still, Jayden may not be a record-holder.

Dr. Thomas Moore, chairman of the Department of Reproductive Medicine at UCSD, said he saw a 14-pound, 10-ounce baby delivered at UC San Diego Medical Center in 1992.

Last year, a Texas woman, Janet Johnson, made news when she gave birth to a 16-pound boy. And the Guinness Book of World Records lists the biggest baby as 23 pounds, 12 ounces, born to Anna Bates of Canada in 1879.

Sigler, who lives in Vista, has more important things on her mind than whether her little boy has broken any records. She’s happy to be able to breathe deeply again for the first time in months.

And she’ll be introducing Jayden to his big sister, 2-year-old Jailyn, who has been told there’s a new baby but thinks it’s another name for her mommy’s belly.

Then there’s a matter of returning some of those baby clothes.

“My sister took back the zero-to-three-month size,” she said. “The 3-to-6-month sizes will be going back, too.”

Sigler said her daughter was average size — 7 pounds, 8 ounces at birth — but bigger babies do run in the family. She and her sister were both just shy of 9 pounds when they were born, which put them in the upper 10 percent among newborns. At 21 inches long, Jayden not only is heavier but longer than the average newborn.

Very large babies like Jayden often are born to women who developed diabetes during pregnancy, but White said that wasn’t the case with Sigler.

“It’s exciting to deliver a baby that big,” White said. “But I’m just very happy the baby is healthy and doing well. That’s what’s important.”